7401

• UCREFRP Catalog Number: 7401
• Author: U.S. Bureau of Reclamation.
• Title: Ruedi Reservoir, Colorado Round II Water Marketing Program, Final Supplement to the Environmental Statement, Fryingpan - Arkansas Projects, Colorado.
• USFW Year: 1989.
• USFW - Doc Type: Billings, Montana.
• Copyright Material: NO

3.27
specimens have been collected. The only observations of natural spawning by
bonytail chub in riverine habitats (Green River) indicated that spawning occurred
from mid-June to early July at a water temperature of 66'F (Vanicek and Kramer,
1969).
The razorback sucker exhibits a scattered distribution in the Colorado River
between Lake Powell, Utah, and Rifle, Colorado (Valdez et al., 1982). The
upstream extent of their distribution is at 2 locations between DeBeque and Rifle
(river miles 220.7 and 223.5). The majority of specimens, 37 (71 percent of
total catch), collected in the upper basin were from 2 abandoned gravel pits
adjacent to the Colorado River near Grand Junction at river miles 163.6 and
117.8. Apparently razorbacks use these areas for resting, feeding, and
spawning. In addition to gravel pits, this species also utilizes backwaters and
runs. The species seems to prefer water with minimal flow (less than 0.1 ft/sec)
and silt-dominated substrates. Razorback suckers usually spawn in April and May
when water temperatures range from 430F to 60OF (McAda and Wydoski, 1980).
However, this species has shown no evidence of successful reproduction during
recent studies (Valdez et al., 1982). Although the species can move 20 miles
or more (McAda and Wydoski, 1980), recent tagging studies suggested a sedentary
behavior (Valdez et al., 1982). Their diet consists mainly of plankton and
insect larvae (Vanicek, 1967).
The Colorado River cutthroat trout (Salmo clarki pleuriticus), downlisted
to a species of special concern on the Colorado state list in January 1985,
occasionally is found in a 2-mile section of the Fryingpan River below Ruedi Dam
(Nehring and Anderson, 1981, 1982). Specimens examined from this section of the
river are classified as almost pure (Behnke, personal communication, 1982).
Apparently, specimens are occasionally found in river sections immediately below
the dam after high flows in Rocky Fork Creek. These cutthroat trout persist
until either they are caught by fishermen or die of old age.
3.3.4 Other Aquatic Communities
Primary production in the open water of Ruedi Reservoir is due largely to
Volvox, a colonial green alga (Nesler, 1979). In shallower inlet areas,
periphyton (attached algae, mainly Glocotrichia and Nostoc) and macrophytes
(Nitella, Elodea, Potamogeton, and mosses) provide important inputs to primary
production and also serve as refugia for benthic animals and fish. Growths of